Corrosion Behavior of Thixoformed AZ91D Magnesium Alloy in NaCl Aqueous Solution

2007 ◽  
Vol 353-358 ◽  
pp. 2611-2614
Author(s):  
Wei Jun Xu ◽  
Ying Ma ◽  
Ti Jun Chen ◽  
Yuan Hao
Keyword(s):  
Corrosion Rate ◽  
Surface Film ◽  
Protective Role ◽  
Spherical Particles ◽  
Protective Film ◽  
Az91d Alloy ◽  
Β Phase ◽  
Corrosion Behaviors ◽  
Lower Corrosion Rate ◽  
Better Than

The corrosion behaviors of thixoformed AZ91D alloy immersed in 3.5% NaCl aqueous were studied by using the weight lose method and observed by scanning electron microscopy and analyzed by electron probe micro-analysis.The results showed that corrosion rate of thixoformed AZ91D alloy was higher in initial stages and decreased as the immersion time increased. Compared with the thixoformed alloy, the change of corrosion rate of permanent mould cast (PMC) alloy was smoothly. The observation on the corrosion surfaces showed that the primary αphase spherical particles were first suffered from corrosion during corrosion testing, and then the eutecticαgrains. the composition of primaryαphase particles in the thixoformed alloy was quite uniform, and thus the protective film of the corrosion products on the alloy surface was more intact. The amount of the eutectic β phase in the inter-particle eutectics was relatively higher and the distribution was more uniform, so the protective film consisted by eutectic β phase was also more intact. That is to say the protective role from the surface film on the thixoformed alloy was better than that on the PMC alloy which was the cause of lower corrosion rate of the thixoformed AZ91D alloy.

Effect of Strontium on Mechanical Properties and Corrosion Resistance of AZ91D

2007 ◽  
Vol 546-549 ◽  
pp. 567-570 ◽  
Author(s):  
Yu Fan ◽  
Guo Hua Wu ◽  
Chun Quan Zhai
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Az91d Alloy ◽  
Nacl Solution ◽  
Strengthening Phase ◽  
Β Phase ◽  
Mg17al12 Phase ◽  
Mechanical Properties And Corrosion

With adding 2% strontium in AZ91D, the ultimate tensile strength and the elongation increased by 10.3% and 55.3%, respectively. This is mainly caused by the refinement of the β phase and the formation of Al4Sr strengthening phase. Furthermore, with adding 2% strontium in AZ91D alloy, the weight loss corrosion rate in 5wt.% NaCl solution decreases to 0.048 mg·cm-2·d-1, which was 33.8 % of the AZ91D corrosion rate. Therefore, the mechanical properties and corrosion resistance of AZ91D could be improved by the addition of 2% strontium, which is due to the refinement of Mg17Al12 phase and the formation of Al4Sr phase.

Corrosion Behaviors of SS310 and IN718 Alloys in Molten Carbonate

2021 ◽  
Author(s):  
Yu Zhang ◽  
Peilin Wang ◽  
Kaiyuan Zheng ◽  
Huayi Yin ◽  
Dihua Wang
Keyword(s):  
High Temperature ◽  
Corrosion Rate ◽  
Molten Salt ◽  
Oxygen Concentration ◽  
Metallic Materials ◽  
Molten Carbonate ◽  
Suitable Material ◽  
Gas Atmosphere ◽  
Corrosion Behaviors ◽  
Lower Corrosion Rate

Abstract Long-lasting metallic materials are key to enabling a robust and reliable molten carbonate electrolyzer. In this paper, the corrosion behaviors of SS310 and IN718 in molten Li2CO3-K2CO3-Na2CO3 under CO2-O2 atmosphere were systematically studied. The results show that IN718 had a lower corrosion rate than that of SS310 because of the higher Ni concentration. In addition, increasing the temperature and decreasing the oxygen concentration can reduce the corrosion rate of both SS310 and IN718. As a result, IN718 is a suitable material to be used in molten salt electrolyzers. Overall, engineering the alloy and molten salt compositions as well as manipulating the gas atmosphere can suppress the corrosion of metallic materials, thereby screening durable metallic materials for high-temperature molten carbonate electrolyzers.

Effect of Film Cooling on Low Temperature Hot Corrosion in a Coal Fired Gas Turbine

2003 ◽  
Author(s):  
Vaidyanathan Krishnan ◽  
J. S. Kapat ◽  
Y. H. Sohn ◽  
V. H. Desai
Keyword(s):  
Low Temperature ◽  
Corrosion Rate ◽  
Hot Corrosion ◽  
Film Cooling ◽  
Gas Turbines ◽  
Primary Source ◽  
Operating Conditions ◽  
Coal Gas ◽  
A Chain ◽  
Lower Corrosion Rate

In recent times, the use of coal gas in gas turbines has gained a lot of interest, as coal is quite abundant as a primary source of energy. However, use of coal gas produces a few detrimental effects that need closer attention. This paper concentrates on one such effect, namely hot corrosion, where trace amounts of sulfur can cause corrosion (or sulfidation) of hot and exposed surfaces, thereby reducing the life of the material. In low temperature hot corrosion, which is the focus of this paper, transport of SO2 from the hot gas stream is the primary process that leads to a chain of events, ultimately causing hot corrosion. The corrosion rate depends on SO2 mass flux to the wall as well as wall surface temperature, both of which are affected in the presence of any film cooling. An analytical model is developed to describe the associated transport phenomena of both heat and mass in the presence of film cooling The model predicts how corrosion rates may be affected under operating conditions. It is found that although use of film cooling typically leads to lower corrosion rate, there are combinations of operating parameters under which corrosion rate can actually increase in the presence of film cooling.

Corrosion behaviors of iron, chromium, nickel, low-carbon steel and four types of stainless steels in liquid antimony-tin alloy

CORROSION ◽  
10.5006/3820 ◽  
2021 ◽  
Author(s):  
Wei Liu ◽  
Huayi Yin ◽  
Kaifa Du ◽  
Bing Yang ◽  
Dihua Wang
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Stainless Steels ◽  
Liquid Metals ◽  
Low Carbon Steel ◽  
Solid Substrate ◽  
Low Carbon ◽  
Corrosion Resistant ◽  
Corrosion Behaviors ◽  
Iron Chromium

Corrosion-resistant metals and alloys towards liquid metals determine the service performances and lifetime of the devices employing liquid metals. This paper studies the static corrosion behaviors of iron, chromium, nickel, low carbon steel, and four types of stainless steels (SS410, SS430, SS304, SS316L) in liquid Sb-Sn at 500 oC, aiming to screen corrosion-resistant SS for Li||Sb-Sn liquid metal batteries (LMBs). The corrosion rates of Fe and Ni are 0.94 μm h-1 and 6.03 μm h-1 after 160 h’s measurement, respectively. Cr shows a low corrosion rate of < 0.05μm h-1, which is due to the formation of a relatively stable Cr-Sb layer that may be able to prevent the interdiffusion between the solid substrate and liquid Sb-Sn. Ni has a high corrosion rate because the formed Ni-Sb and Ni-Sn compounds are soluble in the liquid Sb-Sn. The corrosion products of both pure metals and SS can be predicted by thermodynamic and phase diagram analysis. Among the four types of SS, SS430 shows the best corrosion resistance towards liquid Sb-Sb with a corrosion rate of 0.19 μm h-1. Therefore, a liquid Sb-Sn resistant material should have a high Cr content and a low Ni content, and this principle is applicable to design metallic materials not only for LMBs but also for other devices employing liquid Sb- and Sn-containing liquid metals.

Corrosion Behavior of Duplex Stainless Steel in Industrial White Liquor

CORROSION ◽  
10.5006/2558 ◽  
2017 ◽  
Vol 74 (5) ◽  
pp. 543-550 ◽  
Author(s):  
Luiza Esteves ◽  
Mônica M.A.M. Schvartzman ◽  
Wagner Reis da Costa Campos ◽  
Vanessa F.C. Lins
Keyword(s):  
Weight Loss ◽  
Stainless Steel ◽  
Corrosion Rate ◽  
Duplex Stainless Steel ◽  
Corrosion Behavior ◽  
Extrapolation Method ◽  
White Liquor ◽  
Duplex Steel ◽  
Kraft Mill ◽  
Lower Corrosion Rate

Specimens of lean duplex and duplex stainless steel were exposed at 200°C in industrial white liquor from a Brazilian kraft mill using an autoclave to simulate the same conditions of digester processing. Tafel extrapolation method and weight loss were used to evaluate corrosion behavior of duplex steel in white liquor. The higher alloy steel, although presenting a lower corrosion rate than the lean duplex, presents a more severe selective attack on ferrite, at 200°C and 1.8 MPa, after Tafel extrapolation method in industrial white liquor.

Comparative Assessment of Turbulence Models for Prediction of Flow-Induced Corrosion Damages

2011 ◽  
Author(s):  
Kaushik Das ◽  
Debashis Basu ◽  
Todd Mintz
Keyword(s):  
Corrosion Rate ◽  
Cross Sections ◽  
Volume Fraction ◽  
Solid Phase ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Continuous Phase ◽  
Comparative Assessment ◽  
Solid Particles ◽  
Protective Film

The present study makes a comparative assessment of different turbulence models in simulating the flow-assisted corrosion (FAC) process for pipes with noncircular cross sections and bends, features regularly encountered in heat exchangers and other pipeline networks. The case study investigates material damage due to corrosion caused by dissolved oxygen (O2) in a stainless steel pipe carrying an aqueous solution. A discrete solid phase is also present in the solution, but the transport of the solid particles is not explicitly modeled. It is assumed that the volume fraction of the solid phase is low, so it does not affect the continuous phase. Traditional two-equation models are compared, such as isotropic eddy viscosity, standard k-ε and k-ω models, shear stress transport (SST) k-ω models, and the anisotropic Reynolds Stress Model (RSM). Computed axial and radial velocities, and turbulent kinetic energy profiles predicted by the turbulence models are compared with available experimental data. Results show that all the turbulence models provide comparable results, though the RSM model provided better predictions in certain locations. The convective and diffusive motion of dissolved O2 is calculated by solving the species transport equations. The study assumes that solid particle impingement on the pipe wall will completely remove the protective film formed by corrosion products. It is also assumed that the rate of corrosion is controlled by diffusion of O2 through the mass transfer boundary layer. Based on these assumptions, corrosion rate is calculated at the internal pipe walls. Results indicate that the predicted O2 corrosion rate along the walls varies for different turbulence models but show the same general trend and pattern.

Surface morphology studies and kinetic-thermodynamic characterization of steels treated in 5.0 M HCl medium: hot-dip galvanizing application

2018 ◽  
Vol 65 (2) ◽  
pp. 176-189 ◽  
Author(s):  
Younes El Kacimi ◽  
Mouhsine Galai ◽  
Khaoula Alaoui ◽  
Rachid Touir ◽  
Mohamed Ebn Touhami
Keyword(s):  
Weight Loss ◽  
Corrosion Rate ◽  
Potentiodynamic Polarization ◽  
Phosphorus Content ◽  
Surface Heterogeneity ◽  
Protective Film ◽  
Content Type ◽  
3D Profilometry ◽  
Adsorption Processes ◽  
Hcl Solution

Purpose The purpose of this paper is to study the effect of silicon and phosphorus content in steel suitable for galvanizing on its corrosion and inhibitor adsorption processes in steels/cetyltrimethylammonium bromide combined and KI (mixture)/5.0 M hydrochloric acid systems has been studied in relation to the temperature using chemical (weight loss), Tafel polarization, electrochemical impedance spectroscopy (EIS), scanning electronic microscope (SEM) analysis and Optical 3D profilometry characterization. All the methods used are in reasonable agreement. The kinetic and thermodynamic parameters for each steels corrosion and inhibitor adsorption, respectively, were determined and discussed. Results show that the adsorption capacity for Steel Classes A and B are better than Steel Class C surfaces depending on their silicon and phosphorus content. Surface analyses via SEM and Optical 3D profilometry was used to investigate the morphology of the steels before and after immersion in 5.0 M HCl solution containing mixture. Surface analysis revealed improvement of corrosion resistance of Steels Classes A and B in the presence of mixture more than Classes C. It has been determined that the adsorbed protective film on the steels surface heterogeneity markedly depends on steels compositions, that is, the heterogeneity increases with decreasing silicon and phosphorus content. Design/methodology/approach The effect of silicon and phosphorus content in Steels Classes A, B and C on its corrosion and inhibitor mixture adsorption processes in 5.0 M HCl solution has been studied by weight loss, potentiodynamic polarization, EIS and surface analysis. Findings The inhibition efficiency of mixture follows the order: (Steel Class A) > (Steel Class B) > Steel Class C) and depends on their compositions in the absence of mixture according on their silicon and phosphorus content, that is, the corrosion rate increases with increasing of the silicon and phosphorus content. A potentiodynamic polarization measurement indicates that the mixture acts as mixed-type inhibitor without changing the mechanism of corrosion process for the three classes of mild steels. Originality/value Corrosion rate mild steels in 5.0 M HCl depends on their compositions in the absence of mixture according to their silicon and phosphorus content, that is, the corrosion rate increases with increasing silicon and phosphorus content. The adsorbed protective film on the steels surface heterogeneity markedly depends on steels class’s compositions, that is, the heterogeneity increases with decreasing silicon and phosphorus content.

Wear Evaluation of Plasma Sprayed Oxide and Carbide Coatings

1998 ◽  
Author(s):  
C. Ding ◽  
J. Li ◽  
L. Zhang ◽  
X. Yu
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Smooth Surface ◽  
Surface Film ◽  
Protective Film ◽  
Wear Coefficient ◽  
Sio2 Glass ◽  
Carbide Coatings ◽  
Wear Evaluation ◽  
Plasma Sprayed

Abstract Wear of plasma sprayed Cr2O3 TiO2, Cr3C2-NiCr and WC-Co coatings have been evaluated with a block-on-ring arrangement under dry and lubricated conditions. The results indicated that the wear of the coatings was interpreted in term of subsurface grain fracture which was related to the special microstructure of the coatings such as size, shape and distribution of pore as well as crack. Among the four kinds of coating, Cr2O3 coating possesses the lowest wear coefficient. Water accelerated cracking and fracturing and deteriorated the wear resistance of both Cr3C2-NiCr and TiO2 coatings. Ethanol reduced the wear of Cr3C2-NiCr coating, which was attributed to the formation of a smooth surface film mainly consisting of Cr2O3. Wear of Cr2O3, coating against an Al2O3 ball at high temperature has been also produced. The wear of Cr2O3 coating against Al2O3 ceramics decreased with increase in temperature and load. The reaction between Cr2O3 coating and Al2O3, ceramics at high temperature and the formation of a protective film consisting of Cr2O3, Al2O3 and SiO2 glass on the surface of Cr2O3 coating improved the wear resistance of Cr2O3 coating.

Corrosion Resistance of Mg Alloy with High Zn Concentration Including Impurity Cu

2021 ◽  
Vol 1016 ◽  
pp. 592-597
Author(s):  
Masato Ikoma ◽  
Taiki Morishige ◽  
Tetsuo Kikuchi ◽  
Ryuichi Yoshida ◽  
Toshihide Takenaka
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Mg Alloys ◽  
Mg Alloy ◽  
Second Phase ◽  
Transportation Industry ◽  
Primary Metal ◽  
Cu Content ◽  
Zn Concentration ◽  
Lower Corrosion Rate

Mg alloys are very attractive materials for transportation industry due to their toughness and lightness. Recycling Mg alloys is desired for energy saving that otherwise would be required to produce its primary metal. However, secondary produced Mg tends to contain a few impurity elements that deteriorate its corrosion resistance. For example, contamination of Mg alloy by Cu induces second phase of Mg2Cu and it works as strong cathode, resulting in the corrosion rate rapidly increasing. It was previously reported that the corrosion resistance of Mg with impurity Cu was remarkably improved by addition of alloying element Zn. Addition of Zn into Mg formed MgZn2 phase and incorporated Cu into MgZn2 phase instead of Mg2Cu formation. In this way, since Zn serves to improve the corrosion resistance of Mg, Mg alloy with high Zn concentration may form a lot of MgZn2 and may have better corrosion resistance even with high Cu concentration. In this work, the corrosion behavior of Mg-6mass%-1mass%Al (ZA61) with different Cu content up to 1mass% was investigated. As a result, ZA61-1.0Cu had much lower corrosion rate compared to Mg-0.2%Cu and the corrosion rate was almost the same as that of pure Mg.

Tribological Study of Ecological Lubricants Containing Titanium Dioxide Nanoparticles

2014 ◽  
Vol 658 ◽  
pp. 323-328 ◽  
Author(s):  
Filip Ilie ◽  
Cristina Covaliu ◽  
Georgiana Chisiu
Keyword(s):  
Titanium Dioxide ◽  
Tribological Properties ◽  
Titanium Dioxide Nanoparticles ◽  
Load Capacity ◽  
Surface Film ◽  
Protective Film ◽  
Sem Images ◽  
Base Oil ◽  
Two Samples ◽  
Lubrication Effect

Titanium dioxide (TiO2), belonging to the family of transition metal dichalcogenides (together with molybdenum disulfide (MoS2) and tungsten disulphide (WS2)), is well known for its solid lubricating behaviour. Thin films of TiO2 exhibit extremely low coefficient of friction in dry environments, and are typically applied by mixed in oil, grease or impregnated into porous matrix of powdered materials. Current researches in many areas imply the using of different types of nanoparticles in the composition of oily lubricants. Results of these researches upon the friction couples show that nanoparticles contained by lubricant can improve the tribological properties, the friction-wear reduction and the lubrication effect. When nanomaterials are used to improve lubrication effect, the selection of metal is very important. In this paper, the authors chose for investigating the tribological properties of two samples of TiO2 with the mean diameter of 15 nm (n-TiO2) and 250 nm (m-TiO2), under different friction conditions. The tribological properties of TiO2 nanoparticles mixed in the ecological lubricant oil were investigated using a four-ball tribometer and a block-on-ring tribometer and show the lowering of the friction coefficient in comparison to the lubricant base oil. The finally obtained lubricant is not considered toxic for the environment. The analyses of surface film composition, characterized with the help of X-ray photoelectron spectroscope (XPS) and scanning electron microscopy (SEM) images showed that the deposed nanoparticles form a protective film (TiO3) allowing for an increase in the load capacity of friction couple. XPS and SEM were used to examine the morphology of the wear track, after the four-ball experiment. The main advantage of the nanoparticles is ascribed to the release and furnishing of the nanoparticles from the valley onto the friction metal surface and their confinement at the interface. The TiO2 nanoparticles showed lower frictions coefficient and higher wear resistance as compared to the common TiO2 particles (about 1.5 μm in diameter(c- TiO2)) on a four-ball machine, which were caused by the microstructure of the protective film and serve as perfect intermediate lubricants between the contact surfaces.

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